An alloy is a substance having metallic properties and which is composed of two or more elements at least one of which is a metal.
A metal (i.e. something with metallic properties) is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typically malleable – they can be hammered into thin sheets – or ductile -can be drawn into wires. A metal may be a chemical elements such as iron, or an alloy such as stainless steel.
Most pure metals are either too soft, brittle or chemically reactive for practical use. Combining different ratios of metals as alloys modifies the properties of pure metals to produce desirable characteristics. The aim of making alloys is generally to make them less brittle, harder, resistant to corrosion, or have a more desirable colour and lustre.
List of Examples of Alloys
| Alloy | Components | Comments |
|---|---|---|
| amalgam (dental) | mercury, silver, tin, copper | Hg content is about 50%, Ag is 22-32%. About 1% Zn may also be added. |
| brass | copper, zinc | Cu content is about 65% in the softest brasses and 35% in the hardest brasses. May also contain Pb, Si, Sn, Fe, Al, and Mn. |
| bronze | copper, tin | Sn content is about 12%. Other elements such as Al, As, Mn, Ni, P, Si, and Zn may be added to improve strength or ductility. |
| duralumin | aluminum, copper, manganese, magnesium | Al content is 95%, Cu 4%, Mg 0.5%, and Mn 0.5%. May also contain Si. The alloy is stronger than pure Al for structural use in cars, aircraft, etc. |
| pewter | tin, copper, antimony, bismuth | Sn content is 85-99%. Lead and silver may also be added. |
| solder | tin, lead | Sn content is 5 – 70%. More Sn leads to higher shear and tensile strength. For specialist applications, other elements including Bi, Ag, and Zn can be added. |
| solder (lead free) | tin, zinc, copper | Sn content is 50 – 95%. Cu may be replaced by Ag. |
| steel | iron, carbon | C content is usually lower than 2%. |
| steel (stainless) | iron, chromium, carbon | Cr content is at least 12%; Ni may also be added to inhibit corrosion |
Common Uses of Alloys
- A typical metal is hard and shiny, tough as well as strong. It helps in conducting or carries electricity and heat very well. Metals have thousands of uses in daily life and are often mixed or combined with other metals or substances to form alloys.
- Almost any machine or device which are used for precision instrumentation has at least one metal in it and as the most widely used form is iron we can see the use of steel by using a little amount of non-metal carbon. The use of steel is universal and the day begins with utensils made of steel. The next very common kitchen vessel is aluminium and its alloys.
- The next daily use or rather universally used metal is gold which is worn by almost everyone. The ornaments made up of pure gold is never used by the general public as they are found to be very soft and hence the use of copper or doping with copper makes it little wearable. The doped gold is relatively strong and doesn’t bend as easily as the pure form.
- The door locks and doorknobs are again made up of brass which is again an alloy form of zinc and copper.
- High-performance blades of jets or washing tub or heating elements of microwave and water heater are again nothing but a doped form of the pure metals.
- The common saucepans made up of aluminium never last long but if doped with little magnesium, copper or silicon makes it tough enough to withstand high temperature and do not deform.
- The aircraft body made up of main aluminium is composed of doping with copper, magnesium and manganese which makes it tough, corrosion-free, lightweight and is widely used in aviation industries
